BT5 R3 x64 KDE unable to install from USB, shows black screen
I have multiple laptops, and I'm trying to install BT5 R3 x64 KDE on one of them; the HP ProBook 4320s. I want to have dual-boot, and the computer doesn't have any CD-rom, so I'm installing from an USB. I used to have BT5 R2 x32 KDE on it, which worked seemingly very well (not very familiar with BT/Linux in general). I figured I was going to install R3, so I just deleted two partitions, which probably wasn't a good idea, thinking I could use the same partition... When I try to install from the USB (, which I know is working, as I've tested it on my other computers), I choose "Default" at the beginning, and come to the screen where I write "startx" to get to the desktop, so I eventually can run the script and install it to the hard-drive. I just re-installed Windows 7, because I thought maybe there was a problem because I just deleted the partitions, but I've got the same problem now, after the fresh W7 installation. When I write in "startx", a black screen appears with a blinking, white underline in the top left corner. It blinks two blinks, and then dissapears. Then nothing happens; I've waited for a while... I have no idea what I should do to fix this, and I thought maybe some of the hardware were unsupported, but isn't that unlikely, concidering I did have R2 before? That installation went just fine, no problem like this.
I have very little knowledge of this, but I really want to learn it.
Thanks in advice,